Trends in health service use among persons with Parkinson’s disease by rurality: A population-based repeated cross-sectional study

Background The global burden of Parkinson’s disease (PD) has more than doubled over the past three decades, and this trend is expected to continue. Despite generally poorer access to health care services in rural areas, little previous work has examined health system use in persons with PD by rurality. We examined trends in the prevalence of PD and health service use among persons with PD by rurality in Ontario, Canada. Methods We conducted a repeated, cross-sectional analysis of persons with prevalent PD aged 40+ years on April 1st of each year from 2000 to 2018 using health administrative databases and calculated the age-sex standardized prevalence of PD. Prevalence of PD was also stratified by rurality and sex. Negative binomial models were used to calculate rate ratios with 95% confidence intervals comparing rates of health service use in rural compared to urban residents in 2018. Results The age-sex standardized prevalence of PD in Ontario increased by 0.34% per year (p<0.0001) and was 459 per 100,000 in 2018 (n = 33,479), with a lower prevalence in rural compared to urban residents (401 vs. 467 per 100,000). Rates of hospitalizations and family physician visits declined over time in both men and women with PD in rural and urban areas, while rates of emergency department, neurologist, and other specialist visits increased. Adjusted rates of hospitalizations were similar between rural and urban residents (RR = 1.04, 95% CI [0.96, 1.12]), while rates of emergency department visits were higher among rural residents (RR = 1.35, 95% CI [1.27, 1.42]). Rural residents had lower rates of family physician (adjusted RR = 0.82, (95% CI [0.79, 0.84]) and neurologist visits (RR = 0.74, 95% CI [0.72, 0.77]). Interpretation Lower rates of outpatient health service use among persons residing in rural regions, contrasting with higher rates of emergency department visits suggest inequities in access. Efforts to improve access to primary and specialist care for persons with PD in rural regions are needed.


Introduction
The worldwide burden of Parkinson's disease (PD) has more than doubled over the past three decades with an estimated 6 in 1,000 persons in North America living with the condition, making it an important public health concern [1,2]. PD is a neurodegenerative disorder resulting in a broad spectrum of motor and non-motor symptoms whose incidence rises with age [3]. Previous studies have shown that persons with PD have higher health system use than those without after adjustment for age and sex [4][5][6], contributing to high costs for health care systems [7,8]. The determinants of health service use for people with PD are not well understood and relatively few studies have examined how health service use among persons with PD differs with respect to rural and urban residence and socioeconomic status [9,10]. One study found that higher socioeconomic status was associated with higher rates of hospitalizations among men with PD [9]. The incidence and prevalence of PD in urban areas was found to be higher in the lowest income quintile neighbourhoods in Manitoba, Canada [10]. While the prevalence of PD was also higher in rural areas with the lowest income quintile, no association was noted for incidence [10].
In the general population, living in rural areas has been associated with poorer access to important health services, worse health outcomes, and lower life expectancy [11][12][13]. Persons residing in rural regions may also experience lower incomes and lower rates of educational attainment that place them at an increased risk of poor health outcomes [11]. A better understanding of the differences in health service use among persons with PD by rurality would enable appropriate health policy and health service planning to meet the needs of these populations.
Therefore, the objectives of our study were to compare trends in the prevalence of PD in Ontario, Canada over time and to examine health service use among persons with PD by rural versus urban residence.

Study design, setting and data sources
We conducted a repeated, cross-sectional analysis of the prevalence of PD and associated health service use using linked health administrative databases in Ontario, Canada. These datasets were linked using encoded identifiers and analyzed at ICES. In 2018, the institute formerly known as the Institute for Clinical Evaluative Sciences formally adopted the initialism ICES as its official name. ICES is an independent, nonprofit research institute whose legal status under Ontario's health information privacy law allows it to collect and analyze health care and demographic data, without consent, for health system evaluation and improvement. Ontario is Canada's most populous province, with a population of approximately 14.9 million persons. Ontario residents have universal, publicly funded access to necessary physician services, hospital care, and essential home-based health care services under the province's health insurance plan (see Table 1 in S1 Appendix for full list of databases).

Study population
We identified all persons in Ontario aged 40 years and older who were alive and living with PD on April 1 st of each year from 2000 to 2018 using a previously validated health administrative data algorithm. PD was defined as: three physician billing codes for PD (diagnosis code: 332) in two years each separated by at least 30 days [14] using physician billing data until April 1 st 2020. This algorithm was found to have good performance characteristics when validated against a review of family physician electronic medical record charts as the reference standard (sensitivity: 72.3%, specificity: 100%, positive predictive value: 82.1%, negative predictive value: 99.9% ( Table 2 in S1 Appendix)) and is a refinement of a previous, broader algorithm for Parkinsonism [15].
On April 1 st of each year we identified age, sex, neighbourhood income quintile, 18 coexisting chronic conditions (identified using validated health administrative data algorithms [16]) and whether or not the individual resided in a long-term care facility. Neighbourhood income quintile was defined by linking to Statistics Canada census data using postal codes and is based on the ranking of median income by region [17].

Rurality
The main exposure was rural versus urban location of residence. Rural was defined as living in a rural or small town community with a population size of <10,000 persons outside the commuting zone of larger urban centres according to definitions from Statistics Canada [18].

Health service use
For all persons with PD on April 1 st of each year we calculated rates of health services use from April 1 st to March 31 st for hospitalizations, emergency department visits, family physician visits, neurologist visits, other specialist visits (excluding neurologists), rehabilitation admissions, home care visits and long-term care admissions. Persons residing in long-term care on April 1 st were excluded from the denominator for home care visit and long-term care admission rates as persons in long-term care generally do not receive home care services and are no longer at risk of admission to long-term care, respectively.

Statistical analysis
Standardized differences were used to compare characteristics of persons with prevalent PD by rurality within 2000 and 2018 study years and to compare persons with PD in rural regions across 2000 and 2018 study years [19]. A standardized difference (s-diff) >0.10 was considered a meaningful imbalance. We calculated the overall age-sex standardized prevalence of PD per 100,000 persons aged 40 years and older for each year, as well as age-standardized prevalence by rurality-sex strata to account for known differences in PD incidence, disease progression and outcomes by sex [20]. The standard population was the 2016 Ontario census population [21]. We measured age-standardized rates of health service use per 100 person-years for each year stratified by rurality-sex. For health service use outcomes, individuals were censored on death or loss of health insurance eligibility. The average annual percent change in rates of each health service were calculated using a Poisson model including the count of health service use from the age-standardized rate as the dependent variable and year as the independent variable with the log of the person-years in each year included as the offset term. P-values were used to assess the significance of the annual percent change and were 2-tailed, with p < 0.05 considered statistically significant. Multivariable negative binomial and log binomial models were used to estimate rate and risk ratios and 95% confidence intervals for health service use count and binary outcomes (rehabilitation and long-term care admission only), respectively, during the latest study year (April 1 st 2018 to March 31 st 2019) comparing rural to urban residents.
We estimated three sets of models; unadjusted, age-/sex-adjusted, and fully-adjusted models including income quintile and individual comorbidities. All analyses were conducted using SAS Enterprise Guide Version 7.1 (SAS Institute Inc.).

Ethics statement
The use of data in this project was authorized under section 45 of Ontario's Personal Health Information Protection Act (PHIPA) and does not require review by a Research Ethics Board.

Prevalence of Parkinson's disease
In 2018, the age-sex standardized prevalence of PD was 459 per 100,000 persons. We found a 14% lower prevalence of PD in persons residing in rural compared to urban areas (401 vs. 467 per 100,000).
The age-standardized prevalence was 47% higher among men than among women (550 vs. 375 per 100,000). Within both men and women, we also found a lower prevalence of PD in rural compared to urban areas (men: 480 vs. 561 per 100,000; women: 328 vs. 381 per 100,000). From 2000 to 2018, we observed a modest increase in the prevalence of PD within urban and rural regions by sex, with the exception of women residing in rural regions for which we observed a modest decline (Fig 1).

Characteristics of persons with Parkinson's disease
We identified a total of 33,479 persons with prevalent PD as of April 1 st 2018 and 3,578 (10.7%) resided in rural areas (Table 1). In 2018, persons with PD residing in rural and urban areas were of similar age (median 74 years vs. 75 years, s-diff = 0.07) and were similarly likely to reside in a long-term care home (16.6% vs. 15.9%, s-diff = 0.02). Persons with PD living in rural and urban areas were similarly likely to live in the lowest (22.1% vs. 20.9%, s-diff = 0.03) and highest income quintiles (17.1% vs. 20.4%, s-diff = 0.08). Rural residents with PD were more likely to have comorbid chronic obstructive pulmonary disease (23.6% vs. 19.6%, sdiff = 0.10), but had a modestly lower number of chronic conditions (mean = 2.3 vs. 2.5, sdiff = 0.18). PD duration was similar between rural and urban residents (mean 6.4 years vs. 6.5 years, s-diff = 0.02).

Discussion
In the present study, we found a lower prevalence of PD in rural residents compared to urban residents, with generally increasing trends in prevalence over time (with the exception of women residing in rural regions). Among persons with PD, we observed declines in the rates of hospitalizations, family physician visits, and long-term care admission over time within both rural and urban regions by sex, while rates of other health services (i.e. emergency department, neurologist, and other specialist visits, rehabilitation admissions) remained stable or increased (i.e., home care visits). After adjustment for age, sex, income quintile, year and comorbidities, rates of rates of outpatient health care use (i.e., family physician, neurologist and other specialist visits) and rehabilitation admissions were significantly lower among persons in rural areas, while rates of emergency department visits and long-term care admissions were higher in persons with PD residing in rural areas. The prevalence of PD among persons aged 40 years and older we observed was similar to estimates from other jurisdictions [22,23]. Although the evidence is mixed, some previous studies have found a higher prevalence of PD in urban areas [23]; including studies from the UK [24][25][26], Taiwan [23,27,28], and China [29]. A UK study showed a higher incidence of PD diagnosed in primary care settings in urban compared to rural regions [26]. A Chinese cross-sectional survey of urban and rural counties showed that the prevalence of PD among persons aged 65 years and older was higher in urban compared to rural counties (1.98% vs. 1.48%) [29]. However, recent Australian and Latin American studies have found no difference in the prevalence of PD in rural and urban regions, after adjustment for demographic characteristics [30,31]. Although the exact cause of PD is unknown, genetic and environment factors likely both play a role, including exposures associated with agricultural and industrial occupations [32]. It is possible that higher prevalence of PD observed in urban residents in our study may be related to exposures associated with urban living and/or differences in lifestyle and health system factors. Persons residing in urban areas may have had an increased likelihood of detection of PD due to easier access to specialist care and other healthcare services, which tend to be concentrated in urban areas in Canada [33]. Our finding of a modest increase in PD prevalence over time is congruent with recent studies that have found increasing PD prevalence [1].
Declines in health service utilization, particularly in rates of hospitalization and family physicians over the study period mirror trends seen in other chronic disease populations in Ontario, including hospitalizations for complications of diabetes [34], cardiovascular disease hospitalizations [35], and asthma [36], suggesting that health system factors are playing a role in the observed trends. Declining rates of family physician visits can be attributed to the shift to patient enrollment models in Ontario starting in 2001, whereby changes were made to how physicians were compensated (generally changing from fee-for service per visit compensation to blended capitation models where physicians are paid per patient enrolled in their practice, adjusted for age and sex) [37]. This shift in physician reimbursement has been shown to be associated with fewer visits to family physicians, but no differences in quality of care for persons with chronic diseases [38]. It is possible that improvements in treatments for PD and other conditions are contributing to lower rates of hospitalizations observed. Relatively few studies have examined differences in rates of health care use among persons with PD by rurality. Similar to our findings, a study examining health care use among Manitoba residents with PD found that rural residence was associated with a lower rate of family physician and specialist visits, but found higher rates of hospitalizations [4], while no differences in hospitalization rates were observed in the present study. An analysis of US Medicare beneficiaries with PD also found that rural residence was associated with a decreased frequency of neurologist visits [39].
In Canada very few neurologists and other specialists practice in rural areas [40], which may contribute to the lower rates observed in this study. Persons with PD residing in rural areas in Canada and the United States have expressed difficulties accessing specialist caredue to lack of specialists in their region and having to travel long distances to receive care [41,42]. The large geography of Ontario and centralization of neurologist care in academic centres in southern, urban areas poses difficulties for rural and northern patients trying to access specialist care. Telehealth has been proposed as a potential solution to improve access to specialist care by persons with PD residing in rural regions, although there are concerns regarding the ability of neurologists to assess patients remotely [41]. The Ontario Telemedicine Network (OTN) provides infrastructure to allow for remote neurologist consultations at thousands of locations across Ontario, however, only 18% of total calls to rural areas were for internal medicine based on data from 2008-2014 [43]. During the COVID-19 pandemic, which post-dates our study, there was a rapid shift to virtual and telephone physician care for family physicians, neurologists, and other specialists associated with the introduction of new provincial billing codes [44]. Virtual care has the potential to reduce barriers for persons residing in rural areas to improve access to physician services.
While increased supply and continuity of primary care has been shown to be associated with improved health outcomes at the population and individual levels [45], to our knowledge, there is limited evidence regarding the association in persons with PD. This is an important area for further study. Increased access to neurologist care has been shown to improve patient outcomes and reduce potentially unnecessary health system use and costs for persons with PD [39,46,47]. More frequent neurologist care has been associated with decreases in hospitalizations, emergency department visits, and days spent in skilled nursing facilities [39,46]. Specifically, neurologist care was associated with a decreased risk of hospitalization due to complications of PD, including psychosis, urinary tract infection, and traumatic injury as well as recurrent hospitalizations [39]. In previous research, health care expenditures for inpatient care, home care, skilled nursing facility care, hospice services, and medical equipment were lower for patients with higher levels of neurologist involvement [46]. Neurologist care has also been associated with lower rates of nursing home placement, hip fractures and mortality [47]. Increased access to neurologist care for rural residents with PD in Ontario may reduce the use of more costly health care services.
Lower rates of rehabilitation use in rural residents with PD may reflect increased barriers experienced by rural residents accessing this care such as distance, cost, and transportation issues. Similar issues have been noted by patients attending cardiac rehabilitation in Ontario [48]. Similarly, lower rates of home care visits in rural regions are likely due to challenges related to low population density and large service delivery areas [49]. In the present study, we noted increased rates of long-term care admission in persons with PD in rural regions, which may be related to poorer access to home care services and other health care services for persons needed to support individuals to live longer in community settings [50].

Limitations and other considerations
Although our study had several strengths, there are some limitations that are worthy of consideration. Though we used a validated health administrative algorithm to identify persons with PD, it is likely that we may have under-captured persons with PD, and would not capture those who may have not yet sought care or been diagnosed. It is also possible that the algorithm identified some persons with the broader condition of parkinsonism (i.e., a group of neurological disorders that cause movement difficulties) and it is unclear whether this is differential between rural and urban residents. In addition, there may be residual differences in the severity of PD (which we are unable to measure) or other characteristics between persons with PD residing in rural and urban areas that may have influenced health service use. Finally, we did not examine health care use specifically for PD care, and thus the health care use trends represent the combined effects of PD and its comorbidities.

Conclusions
In this population-based study of persons with PD, we found a lower prevalence of PD in rural areas, as well as lower rates of family physician, neurologist, other specialist and home care visits, but higher rates of emergency department visits and long-term care admission. These findings suggest inequities in health system access for persons with PD living in rural regions. Given the associations between neurologist care and better outcomes in people with PD, future work should focus on understanding and overcoming barriers to specialist care, particularly in rural areas. It is also likely that reduced access to primary care in rural areas is having a negative impact on the health of people with PD, although this remains to be investigated.
Supporting information S1 Appendix. Trends in health service use among persons with Parkinson's disease by rurality: A population-based repeated cross-sectional study. (DOCX) opinions and statements expressed herein are solely those of the authors and do not reflect those of the funding or data sources; no endorsement is intended or should be inferred.